56 PROFESSOR STRUTHERS. 



The Deep Ligaments and Retractor Muscle of the Femur. 

 The posterior ligament (figs. 15 and 16, L), much the 

 largest, resembles the letter Y reversed. Attached to posterior 

 end of femur, undivided part 1^ inch long, as broad as forefinger 

 but not so thick. External division flattened, f to 1 inch broad, 

 directed backwards and a little outwards, 1 to 1| inch long, at- 

 tached to pelvic bone about 2 J inches from femur. Internal divi- 

 sion conical form, slopes backwards and inwards for 3 to 4 inches, 

 attached to great interpelvic ligament and cms penis by a 2-inch- 

 broad base, beginning 1 to 1| inch internal to the pelvic bone. 



On cutting into this limb of the posterior ligament, it is 

 seen to be hollow and to contain a muscle, composed of red 

 striped fibre. This retractor femoris muscle (fig. 16, right 

 side, r.m.) is from 2J to 3 inches in length ; in breadth, at the 

 base 1^ to 2 inches, at the middle 1 inch ; thickness at the base 

 about 1 inch. The enclosing sheath (the ligament) is ^ inch 

 thick. The chief origin of the muscle is, for its outer half, from 

 the interpelvic ligament, and for its inner half from the J to 

 J-inch-thick fibrous wall of the cms penis. There it comes in 

 close relation with fibres of the ischio-cavernosus muscle, but 

 the two muscles diverge immediately. Part of the bundles 

 arise from the inner surface of the sheath at its base, and are 

 inserted into the sheath farther forwards, especially towards 

 the apex, the central part ending in a short tendon which soon 

 becomes identified with the central part of this limb of the liga- 

 ment. The above applies to the ligament and muscle of the 

 right side, that on which the femur is largest. On the left side, 

 the internal limb of the ligament and the contained muscle are 

 much less developed. This muscle will pull the femur back- 

 wards and a little inwards, while the enclosing sheath will serve 

 as a ligament checking forward movement. Considered in 

 relation to the size of the bone on which it acts, this is a large 

 muscle, having a bulk of flesh say equal to the thumb modelled 

 into a cone. The posterior ligament is the great one in all these 

 cetacea possessing a femur, but I have not found in B. mus- 

 culus or in Mysticetus anything corresponding to the inner 

 limb of the ligament and its contained muscle. 



External Ligament of the Femur (fig. 15, m.). A flattened 

 triangular band, 1 inch long, attachments towards promontory 



